Simplfy addon validations and improve coverage

addons/br/nfse/invoices.go

@@ -6,6 +6,10 @@ import (
 )
 
 func validateInvoice(inv *bill.Invoice) error {
+	if inv == nil {
+		return nil
+	}
+
 	return validation.ValidateStruct(inv,
 		validation.Field(&inv.Charges,
 			validation.Empty.Error("not supported by nfse"),

addons/br/nfse/invoices_test.go

@@ -20,6 +20,10 @@ func TestInvoicesValidation(t *testing.T) {
 			name: "valid invoice",
 			inv:  &bill.Invoice{},
 		},
+		{
+			name: "nil invoice",
+			inv:  nil,
+		},
 		{
 			name: "charges present",
 			inv: &bill.Invoice{

addons/br/nfse/item.go

@@ -6,8 +6,7 @@ import (
 	"github.com/invopop/validation"
 )
 
-func validateItem(value any) error {
-	item, _ := value.(*org.Item)
+func validateItem(item *org.Item) error {
 	if item == nil {
 		return nil
 	}

addons/br/nfse/item_test.go

@@ -23,6 +23,10 @@ func TestItemValidation(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "nil item",
+			item: nil,
+		},
 		{
 			name: "missing extensions",
 			item: &org.Item{},
@@ -44,10 +48,6 @@ func TestItemValidation(t *testing.T) {
 			},
 			err: "ext: (br-nfse-service: required.).",
 		},
-		{
-			name: "nil",
-			item: nil,
-		},
 	}
 
 	addon := tax.AddonForKey(nfse.V1)

addons/br/nfse/line.go

@@ -6,8 +6,7 @@ import (
 	"github.com/invopop/validation"
 )
 
-func validateLine(value any) error {
-	line, _ := value.(*bill.Line)
+func validateLine(line *bill.Line) error {
 	if line == nil {
 		return nil
 	}

addons/br/nfse/line_test.go

@@ -26,6 +26,10 @@ func TestLineValidation(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "nil line",
+			line: nil,
+		},
 		{
 			name: "missing taxes",
 			line: &bill.Line{},